1. Field of the Invention
The present invention relates to ionizing radiation sensors, such as X or gamma ray sensors, used in industrial or medical radiographic imaging systems.
2. Description of the Related Art
A sensor of this kind, used for some years in intra-oral dental radiology in an apparatus that permits displaying in real time on a screen the radiographic data furnished and marketed under the designation Radiovisiographie.RTM., has been described notably in European Patent No. 0,129,451 and in U.S. Pat. No. 4,593,400 in the Applicant's name.
Schematically such a sensor comprises a charge transfer array device, also known as a charged-coupled device, (CCD), coupled to a scintillator element and a filter means to impede the passage of the X-rays not transformed by the scintillator element into rays of visible wavelength.
In the sensor in question this filter means is a screen formed by optic fibers provided with metal oxide particles intended to absorb the energy of the X-rays not transformed by the scintillator.
Although the data obtained with a sensor of this type are particularly reliable and workable without reservation by the practitioner, the fact remains that the thickness which must necessarily be given to the screen, for it to fully play its role of filter, constitutes a dimensional limitation affecting the size of the sensor to some extent.
This limitation is overcome with the sensor of the invention which makes use of a means ensuring not only a function of filtering but also of guiding the radiations, the latter function contributing in large measure, as will be understood on reading the description below, to the formation of high quality pictures.